The present invention is in the area of drug delivery and particularly in biodegradable, immunologically active, polymeric devices.
Many adjuvants such as aluminum oxide, polymethacrylate, surfactants, and incomplete Freund's adjuvant rely on a simple "depot" effect, releasing absorbed antigen over a short period of time, ranging from several hours to a maximum of a few weeks.
Recently, Preis and Langer, J. Immunol. Methods 28, 193 (1979); Langer, Methods Enzymol. 73, 57 (1981); and Niemi et al., Lab. Animal Sci. 35, 609 (1985), in an effort to extend the release time, have shown that a prolonged release of small amounts of antigen can be obtained using a polymeric antigen delivery device made of ethylene-vinyl acetate copolymer (EVAc). The prolonged release results in sustained production of serum antibodies over an extended period.
Although this antigen delivery system is an improvement over the prior art, the implanted device has to be surgically removed from the host after completion of the immunization process since EVAc is a nonbiodegradable polymer. It would be advantageous to use biodegradable devices for the controlled release of antigen to avoid this problem, especially in combination with a material having adjuvant activity. A particularly attractive concept is to intentionally design the polymer in such a way that its degradation products have adjuvant properties. This would make it possible to design a device capable of stimulating the immune response while simultaneously releasing antigen over prolonged periods of time.
It is therefore an object of the present invention to provide a polymeric material having adjuvant activity wherein a structure can be formed from the polymer for use in delivering relatively large amounts of a biologically active compound, especially an antigen.
It is a further object of the present invention to provide a material having adjuvant activity with sufficiently good mechanical properties, such as tensile strength, proccessibility and film and fiber formation, to be used as an implantable, controlled delivery device for biologically active compounds.
It is another object of the present invention to provide an implantable, controlled delivery device wherein the polymer degrades after implantation over a predetermined period of time so that surgical removal of the delivery device is not required but is possible during the delivery period, if desired.